USB Self-Idling Techniques

1. A Universal Serial Bus (USB) device including a USB device controller configured to: communicate via a USB bus with a USB host capable of providing current to the USB device; and self-idle the USB device by presenting an idle mode to the USB host and entering a suspend mode while presenting the idle mode to the USB host, wherein: the presenting of the idle mode includes idling differential signal lines of the USB bus and is effective to prevent the USB host from limiting the current provided to the USB device to less than 100 mA while in the suspend mode; and the entering of the suspend mode includes deactivating a clock device of the USB device, causing the USB device to ignore data packets communicated via the USB bus while in the suspend mode, and monitoring a power bus line of the USB bus effective to enable the USB device controller to detect a power cycle event on the USB bus.

2. A USB device as described in claim 1 , wherein the suspend mode is entered in less than 3 milliseconds of presenting the idle mode effective to avoid latency associated with a USB suspend protocol.

3. A USB device as described in claim 1 , wherein the presenting of the idle mode is effective to cause the USB host to provide about 500 mA of current to the USB device if the USB host is a high-power USB host or to provide about 100 mA of current to the USB device if the USB host is a low-power USB host.

4. A USB device as described in claim 1 , wherein the presenting of the idle mode is effective to cause the USB host to provide more than 2.5 mA of current to the USB device.

5. A USB device as described in claim 1 , wherein the presenting of the idle mode is effective to enable the USB device to consume more than 2.5 mA of current while in the suspend mode.

6. A USB device as described in claim 1 , wherein: the clock device of the USB device is a phase-locked loop (PLL) clock; and the entering of the suspend mode causes deactivation of the PLL clock.

7. A USB device as described in claim 1 , wherein the entering the suspend mode is effective to cause the USB device to monitor only the voltage supply line of the USB bus.

8. A USB device as described in claim 1 , wherein the idle mode presented to the USB host corresponds to high-speed operating mode instead of a full-speed or low-speed operating mode previously presented by the USB device.

9. A USB device as described in claim 1 , wherein the USB device controller is further configured to cease to self-idle by leaving the suspend mode in response to the power cycle event.

10. A USB device as described in claim 1 , wherein the USB device controller is further configured to cease to self-idle by leaving the suspend mode in response to reset of the USB bus.

11. A USB device as described in claim 1 , wherein USB device controller is further configured to wake the USB host using an out-of-band (OOB) signal or a general purpose input output (GPIO) signal.

12. A USB device as described in claim 1 , wherein the USB device controller is further configured to: communicate with an access point over a wireless local area network; and poll the access point at predetermined intervals by waking the USB device from the suspend mode to determine if one or more packets are available for communication from the access point, wherein the waking and the determining are performed while the USB device continues to present the idle mode to the USB host.

13. A USB device as described in claim 1 , further comprising a USB physical layer (PHY) to provide an electrical interface to receive and transmit data packets over the USB bus.

14. A method comprising: presenting, at a port of a Universal Serial Bus (USB) device, a high-speed idle mode to a USB host previously in a full-speed or low-speed operating mode and capable of providing current to the USB device over a USB bus; and causing the USB device to self-idle by entering a suspend mode while presenting the high-speed idle mode to the USB host, wherein: the entering of the suspend mode includes deactivating a clock device of the USB device and causing the USB device to ignore data packets communicated via the USB while in the suspend mode; and the presenting of the high-speed idle mode is effective to prevent the USB host from limiting the current provided to the USB device to less than 100 mA while in the suspend mode.

15. A method as described in claim 14 , wherein the USB host is a high-power USB host and the presenting of the high-speed idle mode is effective to cause the USB host to provide more than 2.5 mA of current to the USB device.

16. A method as described in claim 14 , wherein the clock device of the USB device is a phase-locked loop (PLL) clock and the entering the suspend mode causes deactivation of the PLL clock.

17. A method as described in claim 14 , wherein the entering the suspend mode further includes monitoring a power bus line of the USB bus effective to enable the USB device controller to detect a power cycle event on the USB bus.

18. A method as described in claim 14 , wherein causing the USB device to ignore packets communicated via the USB bus includes causing the USB device to ignore a USB resume signal.

19. A method as described in claim 14 , further comprising causing the USB device to leave the suspend mode in response to a power cycle event.

20. A method as described in claim 14 , further comprising causing the USB device to leave the suspend mode in response to a reset of the USB bus.

21. A method as described in claim 14 , further comprising causing the USB device to wake the USB host with an out-of-band (OOB) signal or a general purpose input output (GPIO) signal.

22. A method as described in claim 14 , further comprising: providing a communicative association with an access point over a wireless local area network (WLAN); and polling the access point at predetermined intervals by causing the USB device to wake from the suspend mode to determine if one or more packets are available for communication from the access point, wherein the waking and the determining are performed while the USB device is presenting the high-speed idle mode to the USB host.

23. A Universal Serial Bus (USB) device comprising: a USB physical layer (PHY) to provide an electrical interface to receive and transmit data packets over a USB bus; a USB device controller having a self-idle module to suspend operation of the USB device in less than about one millisecond by: presenting, via the USB PHY, an idle mode to a USB host by idling differential signal lines of the USB bus, the USB host capable of providing current to the USB device; and suspending operation of the USB device while presenting the idle mode to the USB host, wherein: the presenting of the idle mode is effective to prevent the USB host from limiting the current provided to the USB device to less than 100 mA while operation of the USB device is suspended; and the suspending operation of the USB device includes deactivating a clock device of the USB device and ignoring data packets communicated via the USB while in the suspend mode.

24. A Universal Serial Bus (USB) device as described in claim 23 , wherein the USB device controller does not wait for a confirmation from the USB host that operation of the USB bus is being suspended prior to suspending operation of the USB device.

25. A Universal Serial Bus (USB) device as described in claim 23 , wherein the self-idle module presents the idle mode to the USB host when the suspending operation of the USB device is initiated.

26. A Universal Serial Bus (USB) device as described in claim 23 , wherein the USB device receives more than 2.5 mA of power from the USB host when operation of the USB device of the USB device is suspended while presenting the idle mode to the USB host.

27. A Universal Serial Bus (USB) device controller comprising a self-idle module to suspend operation of a USB device by: presenting an idle mode to a USB host capable of providing current to the USB device over a USB bus; and suspending operation of the USB device while presenting the idle mode to the USB host, wherein: the presenting of the idle mode includes idling differential signal lines of the USB bus and is effective to prevent the USB host from limiting the current provided to the USB device to less than 100 mA while operation of the USB device is Suspended; and the suspending operation of the USB device includes deactivating a clock device of the USB device and ignoring data packets communicated via the USB bus while in the suspend mode.

28. A Universal Serial Bus (USB) device controller as described in claim 27 , wherein the self-idle module presents the idle mode to the USB host when the suspending operation of the USB device is initiated.

29. A Universal Serial Bus (USB) device controller as described in claim 27 , wherein the USB device receives more than 2.5 mA of current from the USB host when operation of the USB device is suspended while presenting the idle mode to the USB host.